The correct increasing order of basic character of $Ce(OH)_3$,$Gd(OH)_3$ and $Nd(OH)_3$ is

The number of $f$ electrons in the ground state electronic configuration of $Np$ $(Z=93)$ is ....... .

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$:
Assertion $A$: Size of $Bk^{3+}$ ion is less than $Np^{3+}$ ion.
Reason $R$: The above is a consequence of the lanthanoid contraction.
In the light of the above statements,choose the correct answer from the options given below:

Identify the non-radioactive element from the following.

The electronic configuration of $Yb^{2+}$ is:

The electronic configurations of $Eu$ (Atomic No. $63$),$Gd$ (Atomic No. $64$) and $Tb$ (Atomic No. $65$) are